ObjectivesResearch questions were: 1 How well does the WURSS-21 assess the symptoms and functional impairments associated with common cold? 2 How well can this instrument measure change over time responsiveness? 3 What is the minimal important difference MID that can be detected by the WURSS-21? 4 What are the descriptive statistics for area under the time severity curve AUC? 5 What sample sizes would trials require to detect MID or AUC criteria? 6 What does factor analysis tell us about the underlying dimensional structure of the common cold? 7 How reliable are items, domains, and summary scores represented in WURSS? 8 For each of these considerations, how well does the WURSS-21 compare to the WURSS-44, Jackson, and SF-8?

Study Design and SettingPeople with Jackson-defined colds were recruited from the community in and around Madison, Wisconsin. Participants were enrolled within 48 hours of first cold symptom and monitored for up to 14 days of illness. Half the sample filled out the WURSS-21 in the morning and the WURSS-44 in the evening, with the other half reversing the daily order. External comparators were the SF-8, a 24-hour recall general health measure yielding separate physical and mental health scores, and the eight-item Jackson cold index, which assesses symptoms, but not functional impairment or quality of life.

ConclusionThe WURSS-44 and WURSS-21 perform well as illness-specific quality-of-life evaluative outcome instruments. Construct validity is supported by the data presented here. While the WURSS-44 covers more symptoms, the WURSS-21 exhibits similar performance in terms of reliability, responsiveness, importance-to-patients, and convergence with other measures.

Electronic supplementary materialThe online version of this article doi:10.1186-1477-7525-7-76 contains supplementary material, which is available to authorized users.